Raceway grinder



5 Sheets-Sheet 1 Filed Oct. 5 1951 fad 13 6705 w N M5:

March 29, 1955 p GROBEY 2,704,915

' RACEWAY GRINDER Filed Oct. 5, 1951 5 Sheets-Sheet 2 i i, /M Z fvigy I March 29, 1955 P. A. GROBEY,

RACEWAY GRINDER 5 Sheets-Sheet 5 Filed Oct. 5 1951 I jaw) a jaw] fllmigg/ Wgu/ u Mma I Jag 1 w 45 man! Q March 29, 1955 P. A. GROBEY RACEWAY GRINDER 5 Sheets-Sheet 4 Filed Oct. 5 1951 United States Patent C) RACEWAY GRINDER Paul A. Grobey, Springfield, Vt., assignor to Bryant Chucking Grinder Company, Springfield, Vt., a corporation of Vermont Application October 5, 1951, Serial No. 249,879

6 Claims. (Cl. 51-105) This invention relates to machines for grinding antifriction bearing raceways, more particularly to outside raceways in the inner face of each of which there is a groove between its ends within which the anti-friction elements of the bearing are partly housed.

It has for an object to provide a grinding machine adapted to perform an automatic cycle during which the surface of the groove is ground to finished dimensions.

A further object is to provide for automatic relative motion between the grinding wheel and the work by which the wheel is introduced into the interior of the work piece through one end and is then fed laterally to bring the wheel into grinding contact with the work piece between its ends in a plunge cut to form the groove after which the wheel is retracted transverse to the work sufficiently so that the wheel will clear the work at one side of the groove, whereupon endwise retraction of the tool is effected.

A further object of the invention is to provide means for accurately truing the grinding wheel at a desired time or times in the cycle and to produce an automatic space correction or compensation for each wheel truing and for wear of the wheel.

The invention further relates to a wheel truing mechanism by which the grinding wheel may be shaped to convex contour where the raceway to be ground is for a ball bearing requiring an arcuate ball receiving groove.

The invention is shown herein as embodied in a grinding machine which is primarily controlled mechanically by cams, though the feed motion between the wheel and work piece is controlled by a separate means while the cams are stationary.

For a complete understanding of this invention, reference may be had to the accompanying drawings in which Figure 1 is a fragmentary front elevation of an internal grinding machine embodying the invention.

Figure 2 is a detail sectional view on line 2-2 of Figure 1.

Figure 3 is a top plan view of the machine.

Figure 4 is a detail sectional view to a larger scale on line 44 of Figure 3.

Figure 5 is a fragmentary view looking in the direction of the arrow of Figure 4 showing the wheel truing device at one limit of its dressing motion.

Figure 6 is a fragmentary view similar to a portion of Figure 5, but showing the truing device at its other limit of motion.

Figure 7 is a detail sectional view to a larger scale on line 7--7 of Figure 6. p

Figure 8 is a view mostly in elevation showing the truing device actuating mechanism.

Figure 9 is a detail sectional view to a larger scale on line 9-9 of Figure 8.

Figure 10 is a view partly in top plan with parts omitted and partly in horizontal section through the work feed mechanism, the scale being larger than the plan view of Figure 3.

Figure 11 is a detail sectional view to a larger scale on line 11-11 of Figure 10.

Figures 12 and 13 are elevational views of the truing device actuating and feed cams, respectively.

Figure 14 is a diagrammatic view showing a roller bearing raceway and the wheel truing mechanism.

Figure 15 is a simplified wiring diagram of the control mechanism.

Referring first to Figures 1, 2 and 3, the machine as 2,704,915 Patented Mar. 29, 1955 shown comprises a base 1 on which is mounted in a guide 2 a wheel head 3, this guide 2 being carried by a carriage 4, slidably mounted on the base. Such mounting may comprise a pair of bars 5 and 6 along which the carriage is slidable, the carriage being connected to the end portions of the bars by telescopic dust protectors 7 and 7a. By motion of the carriage 4 the grinding wheel 8 carried by a shaft 9, which forms a portion of the rotor of a high speed motor 2M, may be moved from and toward operative relation to a work piece W (Figure 10). This work piece W is carried by a suitable chuck 10 carried by a rotary work spindle journaled in a casing 11 secured to a work carriage 12. This carriage 12 is mounted for motion as on a pair of parallel bars, one of which is shown at 14, and which is covered over from the carriage bearing 15 to its ends as by the telescopic dust guards 16 and 17.

The relative feed motion between the work and the wheel which causes the wheel to cut into the work is produced by motion of the carriage 12 on its guide bars perpendicular to the motion of the wheel in retracting and approaching grinding position. The work spindle is rotated and to this end, a motor 4M is provided which, as shown, is mounted above the casing 11 and is suitably connected in driving relation to the spindle and chuck as by a belt 20 which passes over a motor pulley 21 and a second pulley 22 carried by the spindle. Opening and closing of the chuck may be controlled by a lever 19 fulcrumed at a fixed point and having a follower 23 bearing on an axially movable chuck operating bar 24. The outer end 25 of this lever may be engaged by the upper end of a lever 26 fulcrumed on a cross shaft 27 and carrying at its lower end a suitable follower bearing on a chuck operating cam 28 (see Figure 3). This chuck operating cam 28, as well as several other controlling cams, is fixed to a main cam shaft 30. This cam shaft carries also a loading cam 31 which through a system of levers at 32 and 33 and a bell crank lever 34 actuates a loading mechanism which takes work pieces from a chute 35 and at suitable times places them in the chuck. All of this mechanism may be the same as that shown in my application for patent Serial No. 236,297, filed July 12, 1951, for Automatic Grinding Machine.

Various other cams which have to do primarily with the subject matter of this invention are also fixed to the main cam shaft 30 as will later appear.

Likewise, as shown and described in my United States Patent No. 2,677,921 granted May 11, 1954, the feed between the grinding wheel and the work is produced by suitable cams on a second cam shaft 36, which application contains claims drawn to the control of the machine by a main cam shaft and a feed shaft, these shafts being actuated intermittently, the one being rotated while the other is stationary.

The relative feed between the grinding wheel and the work piece is produced by a feed shaft 40 (see Figures 2 and 10) which is journaled in a bearing 41 carried by the bed 1 and against one end of which, as shown best in Figure 10, there bears an abutment 42 carried by the work carriage 12. The feed shaft 40, as shown best in Figure 10, is threaded for a portion of its length and is engaged by an internally threaded sleeve 44 which is journaled in fixed endwise position in the stationary bearing 41. A split nut 46 is threaded on one end of the sleeve 44 and acts with a shoulder 47 to fix the sleeve 44 against endwise motion. This sleeve 44 has an arm 48 fixed thereto, which, as shown in Figure 1, is movable along a graduated arcuate plate 49. By rocking of this arm 48 the sleeve 44 is rocked and the shaft 40 is given an endwise motion which changes the position of its end which is engaged by the abutment 42 and allows a weight 43 (see Figure 2) attached to the carriage 12 by a suitable cable 43a to move the carriage 12 in retracting direction, or forces it backwardly as the arm 48 is rocked in the opposite direction. This provides for the normal feed motion of the wheel with relation to the work for a normal grinding operation. However, to feed, during the grinding of the annular groove on the interior of an outer roller or ball bearing raceway, it is necessary to feed the wheel from a retracted position beyond that merely necessary to bring the wheel into contact with the inner cylindrical face of the outer raceway ring. As shown, for example, in Figure 10, it is necessary to feed the wheel relative to the work a further extent to produce the desired recess for the rolling elements of the bearing. Thus an additional plunge cut motion is imparted to the feed and this is produced in accordance with this invention by motion of the abutment 42.

Referring again to Figure 10, this abutment 42 is formed as a head of a rod 50 which is slidably mounted through a sleeve 51. This sleeve is externally threaded for a portion of its length, as at 52, and engages mating internal threads of an outer sleeve 53 which is provided on its inner face with an outwardly extending flange 54 which may be secured to a portion of the carriage 12 as by a screw 55. The sleeve 51 is provided with a gear portion 56 with which meshes a worm 57 fixed to an adjusting shaft 58 (see Figures and 11). The upper end of this shaft 58 carries a graduated wheel 59 provided with a knurled finger portion 60a, and cooperating with this graduated wheel 59 is an indicator member 61a on the top face of the carriage 12. By turning of this shaft 58, it is evident that the angular position of the sleeve 51 may be adjusted, thereby determining the axial position of its inner end upon which normally bears the abutment head 42. This provides for a hand adjustment of the limits of motion of the abutment rod 50 and thereby determines the limits of motion of the carriage 12 as produced by the weight 43 and the rocking of the feed shaft arm 48.

In order to produce the desired plunge cut motion of the carriage 12 which is in addition to the normal feed motion imparted to the same carriage, means are provided for moving the carriage 12 on the rod 50 between two positions, in the innermost of which the sleeve 51 bears against the head 42.

The opposite limit of motion is produced by means which imparts a forward thrust to the carriage 12 along the rod 50 as far as permitted by the engagement of the sleeve 53 on a head 60 threaded on the outer end of the rod 50. This head 60 is engaged by a leaf spring 61 which is secured at one end as by a bolt 62 and a washer 63 to an arm 64 which is pivoted at 65 to a lug 66 projecting from the carriage 12. The opposite end of the leaf spring 61 is allowed a limited amount of motion between the inner face of the arm 64 and a stop plate 68 secured as by a bolt 67 to a portion of the arm 64. The opposite end of the arm 64 from its pivot 65 is pivoted at 70 to a bent arm 71, the opposite end of which is pivoted at 72 to a link 73, pivoted at 74 to a lug 75 also projecting from the carriage 12. The arm 71 is bent so that it clears the pivot 74 and may be moved from the full line position shown in Figure 10 to the dotted line position by the endwise motion of a link 76 which engages with the pivot 72. In the full line position shown in Figure l0, the end of the sleeve 51 is in contact with the head 42, but by motion of the parts to the dotted line position shown in this figure, it is evident that the arm 64 will be rocked inwardly and the carriage 12 will be pushed forwardly on the rod 50 through the spring action of the spring 61 until the dotted line position of carriage 12 and chuck 10 is reached where the outer end of the sleeve 53 may contact the head 60. This provides the desired plunge cut motion which causes the wheel to be projected into the recess in the inner face of the work piece while the normal feed thereafter produces the desired degree of grinding of this recessed face, the outer face of the grinding wheel 8 being shaped to the complemental contour.

The various operations of the grinding cycle, including the actuation of the rod 76 which produces the plunge cut motion and the advancing and retracting motions of the wheel head, the loading mechanism, and the truing of the wheel are all produced, as shown herein, by suitable cams carried by the cam shaft 30. The feed motion which is produced by the rocking of the sleeve 44 and additional feed motion to compensate for wheel wear and truing and produced by turning the shaft 40, is effected by cams on the feed cam shaft 36.

The wheel carriage is moved between wheel retracted position shown in Figures 1 and 3 and operative position shown in Figure 10 by cam mechanism as follows. A bar 80 is secured to a portion 81 depending from the wheel carriage and is normally pressed toward retracted position as by a spring 82. The opposite end of the machine is in condition for the start of a cycle will be in a retracted position shown in Figures 1 and 3 to the right of that shown in Figure 10, and in which the chuck is free to have finished work removed therefrom and a new blank substituted. The wheel will then be given its motion to the position shown in Figure 10 to bring it into line with the recess which is to be ground in the work piece, whereupon the work holder will be given its motion to bring the work against the grinding wheel with the additional feed to insure grinding to the proper depth. The work piece will then be withdrawn by a retracting motion of the work carriage laterally of the grinding wheel axis, and the additional feed to compensate for wheel wear and truing will then be made, this, however, being insufiicient to bring the wheel into contact with the work. The wheel will then be retracted axially, and truing of the wheel may then be effected. The wheel may then be brought back into operative position and the work given its additional plunge cut motion and feed to finish grind the work piece after which the work carriage will be retracted by actuation of the plunge cut mechanism and the wheel will then be moved axially to its inoperative position of Figures 1 and 3.

The actuation of the work carriage to effect the plunge cut and retraction is produced by a cam 90, shown detached in Figure 13, and secured to the main cam shaft 30. This cam is provided with two concentric arcuate portions 91 and 92 which are separated from each other by depressions 93 and 94. Cooperating with this cam is a follower 95 (see Figure l) journaled at the end of a lever 96 which is fulcrumed on the fulcrum shaft 27. The upper end of the lever 96 is operatively connected to one end of a lever 97 (see Figure 3) swingable in a horizontal plane on a vertical pivot 98. The opposite end of the lever 97 is pivoted at 99 to the rear end of the rod 76. The cam follower 95 rides upon the concentric portion 92 of the cam 90 during the loading of the machine, and when the parts are in the position for the rough grind, it drops into the recess 94. This causes the rod 76 to be moved into the dotted line position shown in Figure 10, and produces the plunge cut feed of the work carriage. The main cam shaft 30 is then stationary during the time that the feed cam shaft 36 is being rotated, which effects the normal feed between the work and the grinding wheel. When the feed has progressed to the desired extent, further rotation of the feed shaft withdraws the feed, and a cam 100 carried by the feed shaft 36 contacts and rocks an arm (see Figure 1) which rocks a ratchet feed mechanism shown at 111 stepping around, through a ratchet feed dog 112, a ratchet wheel 113, which turns a shaft 114 connected by a spiral gear 115 (see Figure 2) with a spiral gear 116 keyed to the feed screw 40. This provides the additional feed motion to compensate for wheel wear and truing before the wheel is trued, but it is insufiicient in amount to bring the wheel into contact with the work when the feed arm 48 has been retracted.

The mechanism by which the intermittent rotations of the main cam shaft 30 and the feed shaft 36 are elfected and controlled are shown in the simplified wiring diagram of Figure 15. Referring to this figure, the grinding wheel is normally driven during a grinding operation by the high frequency grinding wheel motor 2M which derives its power from the high frequency lines 150, 151 and 152 through a master switch shown at 153. This grinding wheel motor 2M is controlled by a wheel motor control 2m shown in the lower portion of this figure. The feed motor which drives the feed shaft 36 is shown at 5M. This motor, and a motor 3M, which rotates the main cam shaft 30, and the motor 4M which rotates the work spindle, derive their power from the normal frequency lines 160, 161 and 162 through a main control switch 163. The cam motor 3M which drives the main cam 30, may be connected to the cam shaft through a clutch indicated in the diagram (Figure 15) at 165, and a spring actuated electrically released brake 166 may be applied to stop the rotation of the main cam shaft when the clutch 165 has been opened. The cam motor SM is arranged to be controlled in stopping and starting by the control mechanism 3m. The work motor 4M is controlled in its rotation by the control 4m and the feed motor which is directly connected to the feed shaft 36 is controlled by the controller 5m.

These various control mechanisms derive their energy from the secondary 170 of a transformer 171, the primary 172 of which derives its energy across two of the lines 160 and 162. The various parts are shown in idle condition in this figure. The operator starts the machine by depressing the start button at 175 which completes a circuit from the transformer secondary lead 176 through lead 177, the closed master stop switch 178, leads 179 and 180 through closed switch LS2, lead 181 and 182, start switch 175 and lead 183 through the cam motor control 2m, lead 184, to the other secondary transformer lead 185. This starts the grinding wheel high frequency motor to start the wheel rotating at its fast grinding speed. The closing of the control mechanism 2m also closes the 2m holding switch at 186 which shunts the start switch 175 so that the grinding wheel motor 2M continues to rotate after the start button 175 has been released.

The machine cycle is then started by closing the start switch 190. This establishes a circuit from the lead 181 through lead 191, start switch 190, lead 192, cam motor control 3m and lead 193 to the lead 185. This starts the cam motor 3m and a 3m holding switch 195 is also closed by the control 3m which shunts the start button 190 and maintains the control 3m energized after the start button 190 is released.

A circuit is also established from the lead 192 through the leads 196, 197, through the switch LS7, lead 198, switch LS6, lead 199, the relay CR and lead 200 to the lead 185. The switch LS7 is operated by a cam 202 secured to the feed cam shaft 36 and the switch LS6 is controlled by a cam 203 on the main cam shaft 30. The energization of the relay CR opens a normally closed CR switch at 205 and deenerglzes the motor control 5m so that the feed motor SM is stopped. It also energizes the electrically released brake 210 associated with the feed motor control so that this brake is applied to the feed motor 5M.

The main cam shaft now rotates, and a cam thereon closes the switch LS4 (see Figure 3) which closes a circuit from the lead 196, closed switch LS4, lead 187, work motor control 4m, lead 188 to lead 185 so that the work motor 4M rotates. The main cam motor continues to rotate, a suitable cam thereon bringing the grinding wheel from its retracted position into the position shown in Figure 10, and the cam 90 reaches the angular position where the depression 94 1S opposite to its cam follower which drops thereinto and effects the plunge cut feed of the work with respect to the grinding wheel. At this time, also, the switch LS6 is moved by its cam 203 to break connection with the lead 198 and to make connection with the lead 220. This breaks the circuit from the lead 197, through the switch LS7, lead 198, switch LS6, lead 199, relay CR, lead 200 to the lead 185 and deenergizes relay CR. This allows the CR switch 205 to close and establishes a circuit from the lead 197 through the lead 206, CR switch 205, lead 207, control 5m, lead 208 to the lead 185. This starts the feed motor and also opens the feed brake 210 for this motor 5M. Energiaatlon of the CR relay also opens the CR switch 215 which opens the clutch 165 and it closes the CR switch 216 which applies the brake 166 so that the main cam shaft 30 stops its rotation. It will be noted that the CR switches 215 and 216 are in a rectifier circuit, the rectifier being shown at 220 and deriving its energy from the leads 176 and 185. The feed cam shaft 36 now takes over and acts to rock the feed arm 48 first in feeding direction and then in the opposite direction, and at the end of the feed retraction the cam 100 actuates the compensating feed to feed an additional amount to compensate for wheel wear and truing. When this has been accomplished, the switch LS7 is moved by its cam on the feed shaft 36 to contact lead 220 and complete the circuit to the CR relay. This acts to close the clutch 165 and release the brake 166 so that the main cam shaft 30 again starts its rotation and to open the CR switch 205 so that the feed motor control 5m shuts oif the feed motor 5M and stops the further rotation of the feed shaft. The main cam shaft then begins to rotate with the portion 91 of the cam in operation which retracts the plunge cut mechanism, whereupon the cam 87 on the main cam shaft which controls the position of the wheel retracts the wheel and the dressing of the wheel takes place. The wheel is then brought back by this same cam mechanism into line with the work piece, whereupon its switch LS6 is thrown to its opposite position contacting the lead 198 and breaking the circuit through the lead 220 with the switch LS6. This again deenergizes the CR relay, which, as before noted, stops the rotation of the main cam shaft after the work has been given its plunge motion and starts the rotation of the feed shaft which causes the feed of the wheel with relation to the work to produce the finishing cut. When this has been accomplished and the feed cam has retracted the feed, its switch LS7 is returned to its former position, energizing the relay CR, stopping its further rotation and again starting the rotation of the main cam shaft by closing the clutch 165 and opening the brake 166. It will be noted that the cam which produces the feed compensation for wheel wear and truing is actuated once during each complete rotation of the feed cam. Therefore, as shown, in each grinding cycle there is only one feed for truing compensation so that there is only one truing action, this, as shown, taking place between rough and finish grinding.

As shown in the diagram of Figure 15, provision is made also for stopping the machine whenever the grinding wheel becomes reduced to a predetermined small size. To this end the switch LS2 (Figure 3) is opened by a cam on the main cam shaft 30 at a suitable time in the cycle momentarily, as after the truing, and if at that time the switch LS1 which is closed to its upper position whenever the work carriage is in an extreme feed position indicating that the wheel is too small, is so closed, a light 225 is lighted. Since under these conditions switches LS1 and LS2 are both in position to cut off lead 179 from the lead 181, power is shut ofi from the machine and the machine stops. At those portions of the cycle when the switch LS2 is closed movement of switch LS1 to its upper position, while it will light the light 225, will not cause the machine to stop. This worn wheel responsive mechanism is not claimed herein as it forms subject matter of my United States Patent No. 2,677,921 to which reference has been made previously.

Ball bearing wheel truing mechanism Where the grinding action is to produce a concave groove in the inner face of the work piece, as is necessary for a ball bearing, a wheel truing mechanism arranged for truing the wheel ,in convex contour complemental to the groove to be formed is necessary. Such a truing mechanism is shown best in Figures 3 to 9. Referring to these figures, to the work carriage 12 there is secured a bracket 250 which carries the wheel truing mechanism so that it partakes of the feed motion of the work with respect to the grinding wheel. This bracket 250 has secured thereto a second bracket 251 within which is a pivot 252 for a bell crank lever 253. One arm of this bell crank lever, as 254, has pivoted thereto a link 255, the opposite end of which is pivoted at 256 to the upper end of a lever 257. This lever is fulcrumed on the pivot shaft 27 and its lower end carries a cam follower 258 which bears on a cam 259 shown detached in Figure 12. This cam 259 is fixed to the main cam shaft 30 and cam follower 258 is held thereagainst as by a spring 260 which reacts between arm 254 of the bell crank lever 253 and a fixed anchorage 261 (see Figure 3). The opposite end of the bell crank lever 253 is pivoted at 265 to a rod 266 which is slidably guided through a pair of bearings 267 and 268 carried by the bracket 250. A spring 269 bearing against the bracket 267 on one side and against a collar 270 on the other side and secured to the rod 266, normally holds this rod retracted as far as permitted by the collar 270 engaging the bracket 268 and with its head 271 spaced slightly from a follower roll 272 journaled on an arm 273. This arm 273 is carried by a rock shaft 274 which carries a second arm 275 connected through a curved link 276 with a yoke 277. This yoke 277 is provided with spaced cone pivots 278 and 279 (see Figure 7) which journals it in a frame 280. This frame 280 is rockably carried by the bracket 250 on an axis at 281 about which it may be swung from the retracted position shown in Figure 4 to the operative position shown in Figure 8 in which an adjustable stop screw 285 carried by a tail portion 286 of the frame 280 impinges upon a stop lug 287 forming part of the bracket 250. The yoke 277 carries adjustable thereon a diamond truing point 290. As shown in Figure 7, this point is carried by a block 291 which is supported by a pair of leaf springs 292 from a portion 293 of the yoke 277, an adjusting screw 294 threaded through a portion of the block 291 and bearing on a portion 295 of the yoke 277, serving to adjust the block 291 against the action of the springs 292, this being an adjustment toward the grinding wheel 8 when the truing device is in the operative position shown in Figures 7 and 8.

The angular position of the frame 280 about its axis 281 is determined by a link 300 which is pivoted as at 301 at one end to a portion of the frame 280 and this link 300 has a sleeve 302 welded thereto through which is slidably guided a rod 304 (see Figure 9) provided with a head 305 at its inner end. The opposite end of the rod 304 is journaled on a ball pivot portion 308 of the pivot 265, so that as the pivot 265 is moved forwardly as viewed in Figure 3, the rod 304 is pressed downwardly and may rock from the position shown in Figure 4 about the ball 308 into the position shown in Figure 8. A coil spring 306 surrounds the rod 304 and bears at one end against the sleeve 302 and at its other end against a collar 307 secured to the rod 304. This insures that when the bell crank lever 253 is rocked to bring the rod 304 forwardly, as viewed in Figure 3, or from right to left as viewed in Figures 4 and 8, the frame 280 is rocked downwardly until it is stopped by impingement of the stop 285 on the lug 287. In this position of the parts, the truing diamond 290 is in position to start its truing action, being then in the angular position shown in Figure at one end of the curved portion of the wheel contour in which position it is normally held by a spring 310 coiled about the shaft 274 and having one end at 311 engaged with the arm 275 and the other end hooked to the frame 280 at 312. In this position of the parts a portion of the arm 273 engages an adjustable stop screw 314 carried by a web member 315 of the frame 280, further pivotal motion of the frame 280 being stopped by the engagement of the screw 285 on the stop lug 287. Further motion of the bell crank lever acts to depress the spring 306, allowing the rod 304 to take the dotted line position shown in Figure 9, but during this motion of the bell crank lever 253. the head 271 of the rod 266 engages the follower roll 272 and rocks the shaft 274, causing the truing diamond to be rocked about the centers 278 and 279 from the dotted line position shown in Figure 5 to the full line position shown in Figure 6, thus causing the diamond to true the wheel to the desired convex contour. On reverse direction rocking of the bell crank lever 253, the rod 266 is retracted, allowing the diamond to be swept back in its curved path by the spring 310 until the head 305 of the rod 304 engages the sleeve 302, whereupon further retracting motion of the bell crank lever 253 returns the frame 280 to its inoperative position of Figure 4.

From an inspection of the cam 259, as shown in Figure 12, it will be evident that the diamond holder is lowered to dressing position while the cam passes through a are, that it is rocked across the face of the wheel and then returned in two stages each of 61 rotation, is then returned to retracted position during a 17 rotation, being thereafter idle during the remainder of the rotation of this cam and the cam shaft 30.

Where a roller bearing is to be ground, as shown in Figure 14 at W1, it is of course unnecessary to provide for the movement of the truing device in an arcuate path, it being merely necessary to cause the wheel 325 to traverse the truing device 326 as the wheel is moved between retracted and operative axial positions. The truing device will be carried by the work carriage to move therewith as illustrated in Figure 14.

From the foregoing description of certain embodiments of this invention, it should be evident to those skilled in the art that various changes and modifications may be made without departing from its spirit or scope.

I claim:

1. In a grinding machine, a work holder, a grinding wheel holder, means supporting one of said holders for motion transverse to the grinding wheel axis relative to the other of said holders, feed mechanism comprising cooperating screw and nut members, means operatively connected thereto for turning one of said members to produce feed between said holders, means operatively connected thereto for turning the other of said members for adjustment of said movable holder to compensate for wheel wear and truing, an abutment carried by said movable holder for engagement with one end of one of said members, means for pressing said movable holder in a direction to maintain such engagement, and means operatively connected thereto for moving said abutment from one to another position with reference to said movable holder.

2. In a grinding machine, a work holder, a grinding wheel holder, means supporting one of said holders for motion transverse to the grinding wheel axis relative to the other of said holders, feed mechanism comprising cooperating screw and nut members, means operatively connected thereto for turning one of said members to produce feed between said holders, means operatively connected thereto for turning the other of said members for adjustment of said movable holder to compensate for wheel wear and truing, an abutment carried by said movable holder for engagement with one end of one of said members, means for pressing said movable holder in a direction to maintain such engagement, means operatively connected thereto for moving said abutment from one to another position with reference to said movable holder, and means for adjusting said abutment with reference to said abutment-moving means.

3. In a grinding machine, a worker holder, a grinding wheel holder, means supporting one of said holders for motion relative to the other of said holders, feed mechanism, an abutment engageable with said feed mechanism, a sleeve through which said abutment is slidably mounted for motion toward and from said feed mechanism, said abutment having a head engageable with one end of said sleeve and limiting the motion of said abutment relative to said sleeve in a direction away from said mechanism, means operatively connected thereto for adjusting said sleeve axially with reference to said movable holder, and means operatively connected thereto for moving said abutment toward said mechanism relative to said sleeve.

4. In a grinding machine, a work holder, a grinding wheel holder, means supporting one of said holders for motion relative to the other of said holders, feed mechanism, an abutment engageable with said feed mechanism, a sleeve through which said abutment is slidably mounted for motion toward and from said feed mechanism, said abutment having a head engageable with one end of said sleeve and limiting the motion of said abutment relative to said sleeve in a direction away from said mechanism, means operatively connected thereto for adjusting said sleeve axially with reference to said movable holder, 21 member carried by said movable holder and movable between two different positions relative thereto and against which the opposite end of said abutment from said head may bear, and means operatively connected thereto for moving said member from one to the other of said two positions.

5. In a grinding machine, a work holder, a grinding wheel holder, means supporting one of said holders for motion relative to the other of said holders, feed mechanism, an abutment engageable with said feed mechanism, a sleeve through which said abutment is slidably mounted for motion toward and from said feed mechanism, said abutment having a head engageable with one end of said sleeve and limiting the motion of said abutment relative to said sleeve in a direction away from said mechanism, means operatively connected thereto for adjusting said sleeve axially with reference to said movable holder, a member carried by said movable holder and movable between two different positions relative thereto and against which the opposite end of said abutment from said head may bear, and means operatively connected thereto for moving said member from one to the other of said two positions, said member having a yieldable element for engagement by said abutment.

6. In a grinding machine, a work holder, a grinding wheel holder, means supporting said work holder for motion transverse to the grinding wheel axis, feed mechanism, an abutment carried by said work holder and engaging said feed mechanism for effecting feed and retraction of said work holder by operation of said mechanism, a wheel truing mechanism carried by saidwork holder,

means operatively connected to said abutment for moving said abutment between two positions relative to said work holder both responsive to the feed position of said feed mechanism and in one of which said truing mechanism is in position to be actuated to true said grinding wheel, and means acting on said work holder for holding said abutment in engagement with said feed mecha- 1118m- References Cited in the file of this patent UNITED STATES PATENTS 1,827,659 Jung Oct. 13, 1931 10 Snarry Ian. 19, 1932 Fraser Aug. 23, 1932 Raule Apr. 16, 1935 Cramer Sept. 14, 1937 Stevens Sept. 14, 1937 Cramer Nov. 2, 1943 Beduneau Aug. 22, 1944 English Oct. 10, 1944 Schantz Apr. 16, 1946 Arms et a1 Aug. 29, 1950 Bargren Aug. 21, 1951 

